000
FXUS66 KLOX 272112
AFDLOX
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
210 PM PDT WED AUG 27 2008
.SHORT TERM (TODAY-SATURDAY)...
STUBBORN STRATUS LINGERS NEAR OR JUST OFF THE COAST...WHICH HAS KEPT
TEMPS DOWN OVER THE COASTAL AND VALLEY SECTIONS TODAY. MTNS AND
INTERIOR VALLEYS ON THE OTHER HAND ARE UP A FEW DEGREES...TAKING
ADVANTAGE OF THE WARMER AIRMASS IN PLACE.
INTERESTING NEXT FEW DAYS ON TAP...AS A NARROW RIDGE ALOFT CONTINUES
TO BUILD INTO NORTH-CENTRAL CALIFORNIA BEHIND A PASSING TROUGH
FURTHER TO THE NORTH. THIS 592 DM HIGH WILL DO A FEW THINGS TO OUR
AREA. FIRST OF ALL...THE MARINE LAYER SHOULD SHRINK A BIT
OVERNIGHT...AND NOT SEE AS MUCH OF AN INLAND PUSH AS LAST NIGHT.
WITH THAT SAID...THE MARINE LAYER SHOULD REMAIN ALONG THE COAST AND
WILL KEEP TEMPS MODERATED. HIGH TEMPS WILL SOAR HOWEVER OVER THE
INTERIOR...WITH TRIPLE DIGIT TEMPS OVER INTERIOR SLO AND SBA
COUNTY...AND TEMPS EXCEEDING 105 IN THE ANTELOPE VALLEY. NO CONCERN
FOR HEAT ADVISORIES AT THIS POINT AS LOWER LAYERS REMAIN QUITE DRY.
FIRE WEATHER CONCERNS WILL EXIST...BUT LACK OF WINDS SHOULD KEEP RED
FLAGS DOWN. TEMPS LOOK TO COOL A BIT ON FRI AND SAT...BUT WILL
REMAIN RATHER WARM TO CLOSE OUT THE WEEK.
LASTLY...WITH THE CENTER OF THE HIGH JUST TO THE NORTH...SOME
EASTERLY FLOW WILL SETUP AT MID LEVELS. SINCE THE AIRMASS IS DRY TO
THE EAST...NO DEEP MOISTURE FLUX OR THUNDERSTORMS ARE EXPECTED IN
OUR AREA ON THU...BUT THE PROLONGED EASTERLY FLOW SHOULD BRING SOME
MOISTURE CLOSE TO LA COUNTY BY FRI. IN ADDITION...THE 12Z GFS AND
NAM SHOW A LITTLE EASTERLY WAVE RIPPLE EMBEDDED IN THE FLOW...EXCEPT
THE TIMING OF THIS FEATURE IS FOR EITHER FRI OR SAT DEPENDING ON THE
MODEL. THE MODELS HAVE ALSO BEEN SINGING DIFFERENT TUNES EVERY
RUN...SO CONFIDENCE IS FAIRLY LOW AT THIS POINT AS TO EXACTLY WHEN
AND WHERE THE BEST CHANCE OF CONVECTION WILL BE. AS OF NOW...SLIGHT
CHANCE WORDING EXISTS FOR FRI AND SAT IN THE LA/VTU MTNS AND
DESERTS. IF THE EASTERLY WAVE MATERIALIZES...THREAT OF CONVECTION
WILL NOT ONLY BE CONFINED TO THOSE AREAS...AND THE LA/VTU COAST AND
VALLEYS MAY HAVE TO BE THROWN INTO THE MIX AS WELL. HOPEFULLY THE
MODELS WILL COME TO SOME SORT OF AGREEMENT SOON WITH THIS FEATURE.
EITHER WAY...MTN AND DESERT AFTERNOON/EVENING CONVECTION LOOKS
FAVORABLE FOR FRI OR SAT...OR MAYBE BOTH. LIKE ALWAYS WITH
SUMMERTIME CONVECTION...FLOODING WILL BE A CONCERN. ONCE CONFIDENCE
WITH THE TIMING INCREASES...FLASH FLOOD WATCHES MAY BE
REQUIRED...BUT A BIT TOO EARLY AT THIS POINT TO ADDRESS FURTHER. ONE
LAST WRINKLE IS THE CONCERN FOR DRY LIGHTNING ON FRI...AS LOWER
LEVELS WILL NEED SOME TIME TO MOISTEN. ANY THUNDERSTORMS THAT FORM
EARLY WILL CREATE CONCERN FOR THE FIRE WX FOLKS.
.LONG TERM (SUNDAY-WEDNESDAY)...
BOTH THE 12Z ECMWF AND GFS SHOW A FAIRLY DEEP TROUGH DIPPING INTO
CENTRAL CA ON SUN...AND ALTHOUGH THE EURO MODEL IS SLIGHTLY
FASTER...BOTH MODELS HAVE BEEN FAIRLY CONSISTENT FOR THE LAST 24 HRS
OR SO. THIS TROUGH WILL NOT BRING ANY MOIST FRONTAL BAND TO THE
AREA...BUT WILL HELP TO PUSH THE RIDGE THAT WAS PARKED OVER CENTRAL
CA ON FRI AND SAT TO THE EAST ON SUN. DEEP LAYER FLOW WILL SHIFT TO
A DRY WESTERLY REGIME RATHER ABRUPTLY...AND KILL ANY THREATS OF
AFTERNOON CONVECTION. HIGH PRESSURE WILL ALSO BUILD OVER THE WATERS
OFF THE COAST...WHICH SHOULD ALSO INCREASE WESTERLY FLOW. THIS ALL
ADDS UP TO A RATHER QUICK AND STEEP COOL DOWN SUN AND MON...WITH A
FEW BREEZY SPOTS ALONG THE COAST AND THE MTNS. THE MARINE LAYER
SHOULD ALSO ASSERT ITSELF DEEPER INTO THE VALLEYS. ONCE THE TROUGH
MOVES THROUGH...TEMPS WILL BUMP BACK UP ON TUE AND WED...WITH A
RETURN TO NEAR NORMAL CONDITIONS.
&&
.AVIATION...27/1730Z.
LATEST AMDAR SOUNDING INDICATE MARINE INVERSION AROUND 1900 FT
ACROSS THE LAX BASIN...WITH 12Z VBG SOUNDING INDICATING 1200 FT
INVERSION ACROSS THE CENTRAL COAST. SKIES ARE CLEARING NICELY
LATE THIS MORNING...AND VFR CONDS ARE EXPECTED FOR ALL AREAS
THIS AFTERNOON. HOWEVER...SOME LATE AFTERNOON SEA BREEZE STRATUS
MAY BE POSSIBLE AT KLAX. FOR TONIGHT...EXPECT VERY SIMILAR MARINE
LAYER DEPTH AND COVERAGE...SO VALLEY TAFS WILL LIKELY SEE SOME
CIGS LATE TONIGHT.
KLAX...OVERALL...MODERATE CONFIDENCE IN 18Z TAF. THERE IS A CHANCE
OF SOME AFTERNOON SEA BREEZE STRATUS RETURNING LATER TODAY. FOR
TONIGHT...STRATUS IS EXPECTED TO RETURN AROUND 03Z WITH A MODERATE
CONFIDENCE. THERE IS A CHANCE THAT THE RETURN TONIGHT COULD BE
LATER THAN 03Z. WHENEVER STRATUS DOES RETURN...IFR/MVFR CONDS WILL
BE EXPECTED.
KBUR...MODERATE TO HIGH CONFIDENCE IN 18Z TAF. CURRENT MVFR VSBYS
SHOULD CLEAR UP AROUND 19Z...WITH VFR CONDS EXPECTED THROUGH THE
EVENING. GOOD CONFIDENCE IN RETURN OF STRATUS/FOG TO THE AIRFIELD
AROUND 12Z WITH IFR CONDS EXPECTED.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
NONE
&&
$$
PUBLIC...KITTELL
AVIATION...THOMPSON
WWW.WEATHER.GOV/LOSANGELES
